Litestep ruined my life. I cant go without it now, and when I have to use explorer, I'm always so judgmental "WTF is that doing there!?!, it should be over ther where I can use it!"
And not being able to skin/configure the most essential part of the OS is just irritating.

But really krapduude is right: The best way to learn is to mess with what is allready available (other themes)